FR2665493A1 - Non-dismantleable assembly using snap-fastening - Google Patents

Abstract

An assembly, by snap-fastening, of a hook (18) to a metal sheet (10) is made non-dismantleable by a tongue (16) made in the metal sheet when the orifice 11 is pierced, into which orifice the hook (18) is snapped. The tongue (16) deforms upon the insertion of the hook into the orifice, and comes up behind by elastic deformation in order to be braced up behind the hook and prevent it from disengaging.

Description

INDEPENDENT ASSEMBLY BY LATCHING.

The invention relates to an assembly device by a hook snapping onto a sheet, said hook having a front part with an inclined face capable of being introduced into an orifice made in the sheet and a hooking spout which connects to the front part and has a hooking face which extends perpendicular to the direction of introduction of the hook, coming in the assembled position to hang under the hooking edge of the orifice.

Snap-on fasteners are frequently used in cabinets, especially electrical equipment, to assemble two parts, and this assembly is generally reversible or removable by simple deformation of the hook. This type of assembly also has the advantage of simplicity and reduced cost for irreversible fasteners, and the present invention aims to achieve a non-removable snap-on assembly.

The assembly device according to the invention is characterized in that the edge opposite to the attachment edge of the orifice in the sheet consists of the end of a tongue cut from the sheet, and that the spacing between said edges which defines the width of the hole before the introduction of the hook, is slightly less, at the maximum width of the hook, to the right of the hooking face so that the introduction of the hook into the hole initially causes elastic bending of the tongue in the direction of movement of the hook enlarging the spacing between said edges, and after engagement of the hooking face on the edge of the sheet, an elastic return of the tongue which reduces the spacing between said edges, and locks the hook.

The cutting of the orifice in the sheet metal by stamping reveals a locking tongue which cooperates with the rear face of the hook opposite the hooking spout, and this tongue has sufficient elasticity to bend slightly under the action of the force d 'introduction of the hook into the orifice, and return elastically back, at least partially, when the hook is snapped onto the sheet, to form a stop abutment of the rear face of the hook. The bending of the hook backwards, to disengage the hooking spout from the head, is prevented by the tongue which makes the assembly non-removable.

The front part of the hook is advantageously in the form of a dihedral forming with the hooking face, the hooking beak, and the angle of this dihedron is a compromise between a minimum stroke of introduction of the hook into the sheet and a force sufficient to cause bending of the tongue and / or hook. The hook is advantageously made of plastic, and it is arranged to deform during introduction into the orifice, and to come elastically into the snap-in position at the end of introduction. Depending on the thickness of the sheet, the tongue will be more or less wide, or will have parts of reduced section, facilitating its bending.

Other advantages and characteristics will emerge more clearly from the description which follows, of an embodiment of the invention, given by way of nonlimiting example, and represented in the appended drawing in which: - the figure 1 is a schematic plan view of the sheet of the assembly device according to the invention, the hook being assumed to be removed; - Figures 2,3,4 are sections along the line II-II of Figure 1, showing the hook respectively before its introduction into the orifice, during its introduction, and in the latched position.

In the figures, a sheet 10 has an orifice 11, of generally rectangular shape, two lateral sides 12,13 of which are extended by notches 14,15 defining a tongue 16.

The orifice 11 can be obtained by simple stamping or by any suitable means. One of the edges 17 of the orifice 11 constitutes a hooking edge of a hook 18, capable of snapping onto the sheet metal 10 to assemble or fix a part (not shown), on the sheet 10. The hook 18 has a front part 19, in the form of a dihedron having an inclined face 20 which cooperates, during the introduction of the hook 18 into the orifice 11, with the hooking edge 17. The front part 19 is connected to a flat hooking face 21 which extends substantially perpendicular to the direction of introduction of the hook 18 into the orifice 11, and a rear face 22 of the hook 18 substantially perpendicular to the flat face 21.

In the position shown in Figure 2, before introduction of the hook 18 into the orifice it, the tongue 16 is coplanar with the sheet 10, and ltécartementd1 between the free edge 23 of the tongue 16 defining the orifice 11 with the edge d 'hooking 17, is slightly less than the maximum width d2 of the hook 18, to the right of the hooking beak. During the introduction of the hook 18 into the orifice 11, the inclined face 20 abuts against the hooking edge 17 and causes the bending to the left in FIG. 3 of the hook 18. Simultaneously, the opposite face of the dihedron 19 abuts against the tongue 16, and causes it to bend downward in FIG. 3 to enlarge the spacing dl, enough to allow passage of the hooking spout 24. As soon as this hooking spout 24 has crossed the hooking edge 17 , it hangs under the sheet 10, by elastic return of the hook 18.

This movement to the right in FIG. 4 disengages the rear face 22 of the hook 18 of the tongue 16, which returns elastically upwards in a position reducing the spacing di of the orifice 11. According to the characteristics of the sheet 10 and of the tongue 16, this elastic return can be entire, the tongue 16 returning in the plane of the sheet 10, or partial the tongue 16 remaining slightly bent downwards.

The disassembly of the assembly constituted by the hook 18 and the sheet 10 requires a bending to the left of the hook 18 to disengage the hooking face 21 from the edge 17, but this bending brings the rear edge 22 of the hook 18 against the tongue 16, which constitutes a locking stop. The tongue 16 therefore prevents the disengagement of the hook 18 and disassembly of the assembly. Such disassembly requires bending the tongue 16 downwards, for example using a screwdriver, so as to widen the orifice 11 and to allow the release of the hook 18. The tongue 16 constitutes a locking which nevertheless allows, after special intervention, disassembly of the assembly.

The device is particularly simple and requires no additional operation, and the assembly is robust, the hook 18 being held by the tongue 16. In the example illustrated by the figures, the tongue 16 extends over the entire length of a dimension ' of the orifice 11, but it is clear that this length can be shorter, in particular to obtain greater flexibility in the case of a thick sheet 10. The section of the tongue 16 can also be reduced in certain locations, to increase flexibility or elasticity. The hook 18 is advantageously made of plastic, but any other suitable material is used, the restoring force possibly being provided by a separate spring.

The invention is of course in no way limited to the mode of implementation more particularly described, but it extends to any variant, in particular to that in which the front part 19 of the hook would have a single inclined face 20 on the side of the edge attachment 17, the rear face 22 of the hook 18 extending to the end of the hook, or that where the orifice and the hook 18 would have different shapes, for example rounded.

Claims (5)

1. Assembly device by a hook (18) snapping onto a sheet (10), said hook (18) having a front part (19) with inclined face (20) capable of being introduced into an orifice (11 ) formed in the sheet and a hooking spout (24) which is connected to the front part (19) and a hooking face (21) which extends perpendicular to the direction of introduction of the hook (18), when coming in the assembled position, hang under the hooking edge (17) of the orifice (11), characterized in that the edge opposite to the hooking edge (17) of the orifice (11) in the sheet metal consists of the end of a tongue (16) cut from the sheet (10), and the spacing (dl) between said edges which defines the width of the orifice (11) before the introduction of the hook, is slightly lower. at the maximum width (d2) of the hook (18), in line with the hooking face (21) so that the introduction of the hook (18) into the orifice (11) initially causes an elastic bending of the tongue (16) in the direction of movement of the hook enlarging the spacing between said edges3 and after engagement of the hooking face (21) on the edge (17) of the sheet, an elastic return of the tongue which reduces the spacing between said edges, and locks the hook. 2. An assembly device according to claim 1, characterized in that said orifice (11) is a rectangle of which two opposite sides form said edges and of which the other two  are sides V extended by cutouts (14,15) which define the tongue (16). 3. An assembly device according to claim 1 or 2, characterized in that in the hooking position of the hook (18), the edge of the tongue (16) cooperates or is opposite a rear face (22) of the hook (18) substantially flat and perpendicular to the sheet. 4. An assembly device according to claim 1,2 or 3, characterized in that the front part (19) of the hook (18) is in the form of a dihedral with an edge parallel to said edges in the hooking position. 5. An assembly device according to claim 1,2,3 or 4, characterized in that the hook (18) is made of plastic which elastically deforms when the hook (18) is introduced into the orifice (11 ) to snap elastically on the edge (17) of the orifice (11) as soon as the hooking face has crossed the sheet.